Gas turbine systems are widely utilized in fields such as power generation. A conventional gas turbine system includes a compressor, a combustor, and a turbine. During operation of the gas turbine system, various components in the system are subjected to high temperature flows, which can cause the components to fail. Since higher temperature flows generally result in increased performance, efficiency, and power output of the gas turbine system, the components that are subjected to high temperature flow must be cooled to allow the gas turbine system to operate at increased temperatures.
Various strategies are known in the art for cooling various gas turbine system components. For example, a cooling medium may be routed from the compressor and provided to various components. In the turbine section of the system, the cooling medium may be utilized to cool various turbine components.
Turbine buckets are one example of a hot gas path component that must be cooled. Imperfectly sealed bucket shanks may allow hot gas to enter the shanks, and the hot gas can cause the bucket to fail. For example, in some shanks, when the hot gas entering the shank is above approximately 1900° F., the hot gas can cause shank seal pins to creep and deform, and may cause the seal pins to extrude from the shanks. Further, the hot gas can damage the shank damper pins and the shanks themselves, resulting in failure of the buckets.
Various strategies are known in the art for cooling bucket shank components and preventing hot gas ingestion. For example, one prior art strategy utilizes a high pressure flow of the cooling medium to pressurize the shank cavities, providing a positive back-flow margin for all hot gas ingestion locations on the shank. This positive back-flow margin prevents the hot gas from entering and damaging the shanks. However, the amount of cooling medium that must be routed from the compressor to pressurize the shank cavities is substantial, and this loss of flow through the compressor results in losses in performance, efficiency, and power output of the gas turbine system. Further, a substantial amount of the cooling medium provided to pressurize the shank cavities is leaked and emitted from the shank cavities into the hot gas path, resulting in a waste of this cooling medium.
Thus, a cooling apparatus for a bucket shank would be desired in the art. For example, a cooling apparatus that minimizes the amount of cooling medium routed from the compressor and the amount of cooling medium wasted and lost during cooling of the bucket shank would be advantageous. Further, a cooling apparatus that maximizes the performance, efficiency, and power output of the gas turbine system while effectively cooling the bucket shank would be advantageous.